Firefox 3 was released just this June, and many Firefox fans believe the new version is clearly the best browser you can get. You can make it even better with free add-ons, which integrate directly into the browser and offer loads of useful new features.

Want to increase your security and privacy, synchronize bookmarks among multiple PCs, dress up Firefox tabs, juice up Google, and more? Then I’ve got the add-ons you need. These 15 great downloads make the world’s best browser even better–and, like Firefox itself, they’re free.

Foxmarks Bookmark Synchronizer

Synchronize your browsing bookmarks among multiple PCs–automatically, if you wish–with the Foxmarks synchronizer.

If you use Firefox on more than one PC, you most likely spend a lot of time trying to keep their bookmarks in synch, or else you’ve simply given up the attempt. Otherwise, every time you add, delete, or edit bookmarks on one PC, you have to remember to make the same changes on the others. Not a pretty picture.

The Foxmarks Bookmark Synchronizer solves the problem. Install this tool on each of your PCs, and then, with a click or two, you can synchronize any changes. In fact, you don’t even need to click because you can set the program to synchronize automatically.

The utility offers other benefits as well. Your bookmarks are automatically backed up to a server, so if for some reason you lose them on your PCs, you can always restore them. You can also log into the Foxmarks Bookmark Synchronizer Web site and edit your bookmarks directly there. In addition, if you’re using someone else’s PC, you can use your bookmarks straight from the Foxmarks server.

Download Foxmarks Bookmark Synchronizer | Price: Free

Secure Login

You’ll no longer have to look up or remember site passwords with Secure Login.

If you often log into Web sites and forget or lose your password, Secure Login will be a great time-saver. It directly integrates with Firefox’s password manager, and will log you into any Web site without you having to remember or look up the password. When you’re on a page that requires a login, simply click the icon. Better yet, use a hot-key combination to log in faster.

The program also helps keep you safe online–it prevents hackers from stealing your passwords by halting malicious JavaScript code. It also protects against other password dangers, such as cross-site scripting (XSS) attacks.

Download Secure Login | Price: Free

BugMeNot

Use BugMeNot to protect your privacy at sites that want you to register.

Registering with a Web site often means making a deal with the devil. You give the site information such as your name, e-mail address, and potentially more private data such as your mailing address, phone number, and age.

But what happens with that information? You may be inundated by spam, your name may be sold to mailing lists and advertisers, and possibly worse. But for many Web sites, if you don’t register, you can’t log in and use the site.

This add-on solves the problem. Go to a Web site, right-click in the user name or password field, and select BugMeNot. A valid user name and password will then be entered into the form. You can then use the site without having to register. The add-on works in concert with the BugMeNot Web site, which has many user names and passwords for multiple sites.

Download BugMeNot | Price: Free

Better Gmail 2

Better Gmail 2 lets you customize Gmail in a variety of ways.

From my point of view, Gmail has one primary drawback–it gives you little that you can customize. Basically, what Google gives you is what you get and nothing more. This add-on changes that. It lets you customize Gmail in a variety of ways including skinning it to change its colors and appearance, customizing the sidebar (for example, hiding the spam count), adding HTML signatures automatically to your mail, and more.

Download Better Gmail 2 | Price: Free

Adblock Plus

Adblock Plus lets you choose among various filters–such as EasyList–to block Web-site ads.

Does it seem as if the Internet has become the equivalent of a digital Las Vegas with flashing neon ads wherever you look? Banner ads, ads that are placed willy-nilly, videos that start without your permission–these are just some of the things can distract you and make pages load more slowly.

The answer? Adblock Plus. This add-on blocks just about any ad, but still lets you view the content you want. It claims to eliminate 99 percent of ads on the Web, and that just might be true. When you first start the program, you have your choice of filters to use. If you’re the extremely adventurous type, you can try to build your own, but you’ll be much better off picking one that already exists.

If you browse primarily English-language sites, just choose the EasyList (USA) option. If a banner somehow manages to make it through, right-click it, select Adblock from the context menu, and you won’t see it again.

Looking to keep up with your favorite blogs, news sites, and other fast-changing information resources? You need an RSS reader, which grabs feeds in RSS formats, then lets you browse through and read only what you want. Sage-Too, an update of the venerable Sage reader, makes subscribing to, managing, and reading RSS feeds exceptionally easy. When you’re on a page with an RSS feed, click a button, and Sage will find the feed for you and subscribe to it.

The reader itself is very slick, and displays the feeds inside Firefox, including graphics. You’ll see a summary of each posting; to get to the full posting, click it. It is also easy to reorganize and automatically update your feeds. Plenty of display options exist, as well.

Download Sage-Too | Price: Free

Google Preview

Google Preview adds a thumbnail image of a site to the left of its description in Google search results.

Google may be the best search tool on the planet, but it’s still missing a very useful feature–the ability to preview a site before you visit it. A simple text listing and site description usually isn’t enough.

Google Preview adds such a previewing capability to Google search results by displaying a thumbnail image of each site to the left of its description. That way, you can better see whether it’s a site you want to go to. The add-on also offers site thumbnails when you search using Yahoo.

Download Google Preview | Price: Free

Customize Google

The CustomizeGoogle extension does just what its name suggests.

If you’re a big user of Google (and face it, who isn’t?), you’ll want to install this add-on. It customizes Google in just about any way you could imagine, and no doubt in many ways you couldn’t. For starters, it will block Google’s ads as well as Google analytic cookies (some people believe these cookies invade their privacy). Additionally, it anonymizes your Google user ID.

That’s just the beginning, though. The extension adds links in your Google search results to other search engines, such as Yahoo and Ask.com, among others. It will also filter out search results from Web sites known to be spammers, and it will let you customize not just Google, but its various sites and features such as Gmail and Google News. In short, if you’re a Google user and want to tweak the way Google works, make sure to download this one.

Download CustomizeGoogle | Price: Free

FireFTP

The FireFTP extension puts an FTP utility right into Firefox to handle transfers of big files; it also compares and syncs directories.

The FTP file transfer protocol, one of the earlier ways of transferring files on the Internet, has plenty of life in it. Since many ISPs these days limit the size of files you can transfer via e-mail, FTP remains a very effective way of sharing files.

Normally, you shouldn’t try using your browser to transfer files via FTP–that’s not what browsers are built for. But with FireFTP, you get the best of both worlds with a full FTP client right within Firefox itself. It has plenty of useful features, including the ability to compare directories and subdirectories, keeping directories in sync, and automatically reconnecting and resuming file transfers.

You may become somewhat confused the first time you use the program. Don’t expect to type in an FTP location into the Firefox address bar and get FireFTP to work, because it won’t. Instead, you have to first open FireFTP by choosing Tools, FireFTP. Then create a new account for each FTP site from a button on the top left-hand side of the screen. After that, it’s all straightforward.

Download FireFTP | Price: Free

NoScript

NoScript lets you customize how scripts are allowed to run on a site you visit.

One of the best things about the Web–its interactivity–is also the most dangerous. Tools like JavaScript, Java, and Flash Silverlight make the Web a far more entertaining and useful place. But they can be used in malicious ways as well. You’d like to run only the good interactivity, and leave out the bad. Sounds impossible, doesn’t it?

That’s exactly what NoScript does: It blocks all JavaScript, Java, and Flash Silverlight scripts by default, and then lets you allow them to be run on safe sites. As you browse the Web, a small icon runs in the bottom right of your screen telling you the status of NoScript.

If any scripts are being blocked, you’ll be shown details in a bar at the bottom of the page. To customize how scripts should be run on the site, click the icon, and you’ll be able to allow scripts through from the site or block them–permanently or temporarily–along with other options.

Download NoScript | Price: Free

Video Download Helper

Video Download Helper lets you download clips from YouTube (and many other sites).

Video sites such as YouTube and others are certainly entertaining, and at times even useful. But there’s one problem with them: You can’t download videos to your PC to play them later. You have to revisit the site each time you want to see a video.

Video DownloadHelper does away with this limitation. It will let you download videos from YouTube and many other sites and store them on your hard disk, so you can watch them whenever you want. When you’re on a site, all you’ll have to do is click the Video DownloadHelper icon and save the video. You can also do the same for graphics and audio clips.

Some video and music files can be quite large, so the program gives you the option of not downloading files over a certain size. It can also work with any video converter program that you may have installed to convert videos to more useful formats.

Download Video Download Helper | Price: Free

ColorfulTabs

ColorfulTabs enhances your Firefox tabs.

There’s no two ways around it–Firefox’s tabs are just plain dull. A bit like the Model T, they come in any color you want as long as they’re the same shade of gray. If you’d like to dress up your tabs and make it easier to distinguish among them, you’ll want this simple extension. You can either stick with the default colors, or choose your own color for each tab. You can even have the program remember the color for each URL you visit. You can control more than just the basic color of each tab. You can also have the colors fade, and you can even put a background color on each.

Will this add-on change your browsing life? No. Will it make it more visually pleasing? Without a doubt, and that’s enough reason to give it a try.

Download ColorfulTabs | Price: Free

WOT (Web of Trust)

The WOT extension rates the safety of every site in search results.

It isn’t news that the Web is full of innocent-seeming sites harboring bad intentions: Sites that host spyware or malware. Sites that spam you. Sites that scam you. Sites that invade your privacy, or that children shouldn’t view.

Unfortunately, there’s no simple way to tell the good sites from the bad. WOT, however, acts as just such a screener. It rates every site for trustworthiness, vendor reliability, privacy, and child safety, and shows you the results using simple, instantly interpretable colored icons (red for bad, green for good). When you do a search in Google or another Web site, you’ll see the icons and know what you’re in for if you visit. You can also visit the WOT rating for each site to see why it was given its rating.

It offers other protections as well. When you visit a site with a red rating, you first get a big warning on your screen. That way, you can either navigate away or click through at your own peril. And when you’re on any Web site, click the WOT button in Firefox, and you’ll be shown details about the site’s rating as well.

Download WOT (Web of Trust) | Price: Free

Mini Map Sidebar

The Mini Map Sidebar lets you access mapping services wherever you are on the Web.

Google Maps and other mapping services are among the most useful sites on the Internet. But they do have one inconvenience: You have to visit them to get their information. Wouldn’t it be nice if you could get mapping information no matter where you were on the Web?

The Mini Map Sidebar does just that. Open it as a Firefox sidebar, then drag and drop address names or links to it, and a map of them will open right in the sidebar. You have your choice of map services, including Google Maps, Yahoo Maps, and others. You can then zoom in or out, get directions–in short, do pretty much anything you can do on the mapping site itself. In fact, you can do even more because Mini Map Sidebar includes some nice extras such as traffic information.

Download Mini Map Sidebar | Price: Free

All-in-One Sidebar

The All-in-One Sidebar lets you review your browsing and download history, provides info on the page you’re visiting, and much more.

The Firefox sidebar is one of the browser’s more useful tools, but most likely one of its least used. It serves plenty of purposes–you can browse your history and view your bookmarks there, for instance. And many add-ons, such as Sage-Too, use it as well.

This clever tool lets you quickly switch among all your sidebar panels, and gives you a great deal of information about your Firefox use. Want to see your entire download history in the sidebar? It can do that. It will also show you all of your add-ons with details about each, give you information on the current page you’re visiting, and more.

If you don’t regularly use the Firefox sidebar, give this add-on a try, and you might change your mind. And if you do use it regularly, this one will be a keeper.